mot emissions

[K4000JB]

hi
just after some advice i am doing some work on a relatives 1.6 k plate eunos and it has failed the mot on the idle emissions being >6% but the fast idle emissions were spot on the 0.20% limit it has 2 sensers one on the down pipe and one on the cat(although this one is much smaller than i would expect it to be).Also it needs a lower front shock bush(bilstein shock)which i cant seem to find on the mx5 parts site.

thanks for your help in advance

[The AJP Griff]

bump!surely someone can answer this?i'm interested also

[swansea v6]

Can't really help but the scond sensor, the one on the cat is not needed. It was fitted to imports and is a sensor that picks up if the cat is too warm.......mine was binned when the cat came off

[Combover]

I thought the Mk1 only had one O2 sensor anyway, so I doubt it's the one from the cat that's the issue.

[MX-5 Lazza]

The second sensor isn't an O2 sensor - it just detects a failed cat but it seems to fail more often than the cat does. Most people remove them from the cat but leave it connected to the harness. Just tie it up out of the way somewhere.
As for the emissions - the first things to check are the obvious ones - plugs & leads. Try cleaning the O2 sensor (I'm told you can take it out and wipe it with a stiff cloth but don't touch it with a wire brush!!!). After that I have no idea.

[K4000JB]

hi guys just an up date the second sensor is just a heat sensor. i replaced the lambda sensor but the emissions rose further. in the end it looks as though someone had been tinkering with the afm by slackening off the spring it increases the mixture. so tighening the spring has brought the mixture down to an acceptable 0.3% this an easy fix if you find your car fails the mot on idle emissions(only for older cars with the older spring type afm). why they bothered to do this is anyones guess because it doesnt increase the amount of fuel throughout the rev range just idle.
thanks for your replies